10 yr European retrospective study of haemophagocytic lymphohistiocytosis found 3345 deaths due HLH from 29 countries. Crude mortality rate = 5.3 per 10million PYs (range: 1.1-11.3). From 2011 to 2021, increasing from 3.9 to 6.6/10millPYs, varying by country, sex, age. https://t.co/58gCQ72saF